Showing a code 54 on 95 k1500 5.7 only have 5.3 volts with key on and 3.7 while cranking. Replaced fuel pump and oil pressure switch and relay is good as well as the fuel pump ground. Just wondering if anybody has input on where to start tracing this problem down. I'm quite sure that the voltage should be higher and I think this is why i'm getting a no start condition.

 

You're reading this with a voltmeter, is the leads attached solid to the fuel pump terminals? I see your post of voltage drop while cranking, however you should read battery voltage. If you battery voltage is 5 volts, you need to look into battery/charging system.

 

Make sure you have a good ground at the fuel pump. Check the voltage again making sure your meter is at a good ground. If you are still only getting 5.3 volts check the voltage coming from the relay at the relay. If still only 5.3 volts, keep going back till you find 12 volts.

 

Could anyone tell me where to find the spot where the fuel pump grounds on a 99 blazer 4x4 4.3 . new fuel pump! issues with fuel gauge.